Thermal Head Protective Layer Thermal Expansion Mismatch
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Solution Overview
Problem
The thermal head described in Patent Literature 1 faces a possibility of layer separation due to the difference in thermal expansion coefficients between the SiO2 first layer and the Ta2O5 second layer, leading to potential wear and adhesion issues during printing.
Innovation Solution
A thermal head with a protective layer comprising a first layer of silicon nitride or silicon oxide and a second layer of tantalum oxide and silicon oxynitride, which enhances adhesion and reduces the likelihood of separation, thereby improving wear resistance and slipperiness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a Ta2O5 second layer is disposed on a SiO2 first layer, then the protective layer can be formed with appropriate material properties, but layer separation occurs due to difference in thermal expansion coefficients
Solution Approach 1:
The patent introduces a first layer made of SiO2 as an intermediary between the substrate and the Ta2O5 second layer. This intermediate layer acts as a buffer that reduces the thermal expansion coefficient mismatch between the substrate and the Ta2O5 layer, preventing layer separation while maintaining the protective function of the coating structure.
Solution Approach 2:
The patent employs a composite protective layer structure consisting of multiple materials (SiO2 and Ta2O5) with different properties. By combining these materials in a layered composite structure, the patent achieves both the protective function of Ta2O5 and the thermal expansion buffering capability of SiO2, resolving the adhesion problem.
2Ease of manufacture
If the protective layer structure is simplified, then manufacturing becomes easier, but wear resistance and slipperiness performance deteriorate
Solution Approach 1:
The patent divides the protective layer into two distinct functional layers: a SiO2 first layer for thermal expansion management and a Ta2O5 second layer for wear protection and slipperiness. This segmentation allows each layer to be optimized for its specific function while maintaining a relatively simple overall manufacturing process using standard deposition techniques.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively decreases the possibility of layer separation, enhances wear resistance, and maintains slipperiness, resulting in improved performance and longevity of the thermal head during printing processes.
Implementation Method 1
there is a possibility that the second layer will be separated from the first layer due to the difference in thermal expansion coefficient between the first layer and the second layer
Implementation Method 2
an electric resistor connected to the electrode, part of which serves as a heat-generating section
Data Source
AI summary
There are provided a thermal head capable of decreasing the possibility of occurrence of layer separation in a protective layer, and a thermal printer equipped with the same. A thermal head includes a substrate; an electrode disposed on the substrate; an electric resistor connected to the electrode, part of which serves as a heat-generating section; and a protective layer disposed on the electrode and on the heat-generating section. The protective layer includes a first layer containing silicon nitride or silicon oxide; and a second layer disposed on the first layer, containing tantalum oxide and silicon oxynitride.